Holding-circuits for toll-switching trunks



0. H. LOYNES. HOLDING CIRCUITS FOR TOLL SWITCHING TRUNKS.

APPLICATION FILED DEC.23, i918.

Patented Nov. 23, 1920.

UNITED STATES" PATENT OFFICE.

OWEN ir. Lorrains. or Weens-inea, NEW JERSEY, AssreNon To AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION or NEW YORK.

HoLDING-oiitonrrs non 'roLLY-sWIrCHIfNG TRUK'S.

Specification of Letters Patent. atnted NOV. 23, 1920.

Applicaties mea December 2s, .1918. serial No. 268,063.'

To cZZfw hom "it my concert,

Be it known that 1 @wen H. LoYNrJs, residing` at VVoo'dridge, in the 'county of Bergen and State of New Jersey, have invented certain Improvements in Holding-Circuits ior Toll-Switching Trunks, oi which the 'Following is a specication.

This invention relates to telephone circuits and'more particularly to circuits employed in connection with the establishment of long'distance toll connections.

When a subscriber indicates to an A operator at a local oliice that a long distance connection is desired it is customary 'for the A operatoi` to connect the subscriber .with a trunk leading` to a toll oilice at which the trunk terminates before a recording operators position. The recording` voperator communicates over the trunk and ascertains :from the subscriber the connection desired and then proceeds to enter this information upon. a ticket. T he recording operator then communicates over an order wire with a B operator at the local oihce in which the calling' subscribers line terminates and orders the callin@ snbscribers line connected to a toll switching trunk extendingbetween the local oiiice and the toll oiiice. This connection having been established the recording operator associates a holding 4circuit with the toll switching trunk toV hold the connection thus established in condition for cont pleting; the longdistance connection when the desired .party is available. During the time which elapses while the various operations necessary to completing the call take place the calling subscriber may hang np his receiver.

The recording; operator having made out the ticket passes it to edirectory operator, in case it is necessary to obtain Jinrther information with reference tothe called `si`1bscriber. lt all necessary information was secured by the recording? operator, the ticket is passed directly to a toll operator for the purpose of completing' the connection.` The directory operator, upon receiving' the ticket, associates a holding' circuit with the toll switching' trunk which is connected with the calling' subscribers line, and thereby transmits a disconnect signal to the recording' operators holding; circuit so that the recording' operator may now disconnect her holding circuit, the toll switchiim trunk being' in the meantime held by the holding circuit oi the directory operator. The-directory operator,

`upon obtaining' the necessary information lor completing' theV call, passes the ticket on to a toll operator or the purpose of cornpleting the connection.

t is one ci the objects of this invention to provide a holding circuit for a toll operator olf'such a character that, upon associating the holding circuit with a toll switching trunk, a `disconnect signal will be transmitted to Vthe holding circuit of the directory 'operator or the recording operator as the case may be. 'i Y i A further object of the invention is to "so arrange the holding;` circuit oi the toll operator that whenrit is associated with a toll switching trunk and thereafter a Asimilar holding circuit is associated with the truni'r by another toll operator to whom the 'ticket for some reason has been passed in orderito complete the connection, a disconnect sigf nal will be received by the first ho'ldiir'g,v circuit so that the first toll operator may disconnect the same from the toll' switching`r trunk. i y i A still further object of the invention is to provide a holdin@ circuit for a toll operator of such character that when, Vupon the setting up or' a connection between the vcall*- in'ef subscriber and the wanted subscriber, a ten @crdis associated with the @Bewitchingr 'triinkf 'al disconnect 'Signal willbe received by the holding' circuit so that the saine may, be removed from the toll switching' trunk. 1 f A other and farther Qb'iects ofthe investies vv'ill'be lclear from 'the' following description when read in connection with the aibcorli;d pan'ying drawing, the 4figure 'oij which illusfl'tes aprieirdenbflilt 0f' th, tin, It 'is bellffd lllat'tl @params 1S '0f such nature that it y best be anden sind 'fromme desinnee 0f the been@ which as follows z' i "Assuming" that a recordingv voperati-)r has obtained vfromV the calling;y subscriber vthe necessary information to initiate the estab,- lishment of a long distance connection an i that in'` response thereto ythe recording operator has made out the usual ticket and ordered the calling subscribers line con-` nected to a toll switching trunk T, the re# cording operator inserts the plug P1 of a holding circuit C1 in the jack J1, through which the toll switchingl trunk T terminates tery is bridged across the trunk, but when .the receiver is removed from the hook, battery is disconnected from the trunk. 'Assuming that the calling subscriber has hung up his receiver' to await the establishment of .the desired connection, the relay 1 will be energized by reason of the battery connection bridged across the toll switching trunk l and at its front contact shuntsl the subscribers signal lamp 2, thereby preventing it from glowing. Y The high resistance rmal-, ginal relay 3 associated with the sleeve circuit ofthe holding circuit is not operated when the plug P1 is inserted in the jack J1 as the sleeve conductor of the trunk is connected to ground through a resistance et.

Assuming that the recording operator se cured from the calling subscriber all of the necessary information for completing the connection and that the recording operator has also in the meantime passed the ticket containing the desired information to the toll operator at the first toll operators position, forthe purpose of completing the connection, the toll operator upon receiving the ticket will at once insert the plug l), of the holding circuit C3 in a multiple jack J3 of the toll switching trunk. This is done for the purpose of holding the toll switching trunk T while the connection is being established. The hold-circuit C3 may be used as a link circuit, but in practice is merely a one-ended circuit adapted to associate the talking set of the operator with the trunk. A circuit is now completed lfrom battery over the middle'back contact of relay through the winding of high resistance re# lay 6, over the sleeve contacts of plug P3 and jack J3, over the sleeve circuit of the trunk T and thence to ground over the sleeve contacts of the jack J1 and the plug P1 and through the winding of the high resistance marginal relay 3 in parallel with resistance 4.. The high resistance relay 6 is energized over the circuit above traced but owing to its high resistance the current flow is insufficient to operate the marginal relayB. i Relay 6 upon being energized completes a circuit from ground over the front contact of said relay and through the winding of relay 7 to battery. Relay 7 upon being energized, at its upper front contact completes the talking circuit so that battery from the toll switching trunk liows through the winding of holding relay 8.. Holding relay 8 opens the circuit of the subscribers signal lamp 9 which otherwise would have been completed by the energization of relay 7, said circuit extending from battery over the lower front contact'of relay 7 lower back contact of relay 5, lower normal contact of holding key K3, back contact of relay 8 and through the lamp 9 to ground., The relay 6 alsocompletes a circuit from ground over its front contact, through the winding of low resistance marginal relay l0, over the upper back contact of slow acting relay l1, through the winding of high resistance re lay 6 and over the middle back Contact of relay 5 to battery. Owing to the high resistance of relay 6, marginal relay l0 does not receive sufficient current to attract its armature. Accordingly a further circuit is completed by relay 6 from ground over the front Contact of said relay, over the back contact of marginalrelay l0 and through the winding ot slow acting relay ll to battery.

Relay 11 upon being energized opens the circuit of relay 10 and completes circuits for the differential relay 12 as follows:

From' battery through the low resistance winding of relay 12 to point 13 where the circuit divides one path continuing through the lower high resistance winding of relaVT l2 and over the lower front Contact of relay ll to ground. Another path entends from point 13 through the low resistance winding of relay lll, over the upper front contact of relay 1l, over the sleeve contacts of plug l?, and jack J3, over the sleeve circuit of the trunk T, sleeve contactsof j ack J, and plug P,V and through the winding` of marginal relay 3 to ground. The marginal relay 3 now has in series with its winding only the low resistance lwinding of relay'lQ and the winding ofrelay le which is also o f low resistance. Consequently the current flow through relay irl is sulicient to energize said relay, which at its left hand front contact `completes a circuit for theV disconnect lamp' l5. T he windings of rela-y i2' are difierentially arranged and are so proportioned that with the circuits as above described said relay l2 will not be energized. lRelay ist will 'be energized, however, and at itsupper front vcontactcompletes a locking circuitfortlierelay ll. '4 The recording operator upon observing the glowing of the disconnect lamp l5 withdraws the plug lo), .from the jack (l, of the toll switching trunk, thereby restoring the holding circuit C1 to normal. The discon` nection of the high resistance relay 3 from the sleeve circuit of the trunk does not suficiently vary the current flow through the windings of the relay i2 to operate said relay, as ground is still connected to the sleeve of Vthe'trinok through the resistance fi.

izo

-rst position that the plug withdrawn. Relay l2 upon being energized- Consequently the relay 14 of the holding circuit C3 remains energized but the ditl'erential relay 12 remains denergized.

ln the normal course events the iirst toll operator now proceeds to complete the connection. li, however, the iirst operator should be overloaded the ticket ot the con1 nection here under consideration might be passed to a second operator who upon receiving the saine would insert the plug l2 oi' the holding circuit C4, (which is similar to holding circuit C3), in the jack J4 of the toll switching trunk T. A circuit is thereby completed from battery over the middle back contact of relay lo, through the winding oi' high resistance relay l?, over the sleeve contacts of plug l?"L and jack J4 and over the sleeve circuit ot the trunk T through resistance l to ground. Relay 17 is now energized and at its lower front Contact completes the circuit of relay 189 which upon being energized completes a talking circuit and prepares a circuit of the lamp 19 in a manner similar to that described in connection with the lamp ot the holding circuit C3. Y

.Relay 17 also completes a circuit from ground over its ,iront contact through the winding of the 'low resistanc marginal relay 20, over the upper baclr contact of slow acting relay 2l, over the sleeve contacts ci: plug P4 and jack J4, over the sleeve coutacts of jack J. and plug P3, over the upper front contact or relay lli through the winding of relay 1e*- and through the upper low resistance winding ot relay l2 'to batte j is the circuit just traced `ncludcs only three low resistance windings, sutiicient current flows through the winding ott relay 2G to energize the sance7 and said relay upon attracting its armature opens the circuit et the slow acting relay betere said relay has had time to pull up. he current tlowing through the upper low resistance winding of relay 12 is also increased to such an extent that the diii'erential relay 'l2 is energized and completes the circuit ol? the disconnect lamp 22 of the iolding circuit C3, thereby indicating to the operator the P3 should be also completes the circuit oi relay o7 which at its middle contact opens the battery connection through the high resistance relay Relay 6 is thereupon denergized and opens the circuits of relay 7 and 10. Relay ll,A however, remains energized as it locked up over the 'front Contact et relay l The lirst toll operator u n olz; the glowing oi" signal lamp 22 withdraws the plug P3 from the jaclr thereupon disconnecting battery from the slcei'c Contact of the jack J3 and releasing' relays lll and This operation also results in the deenergization of the marginal relay 2O ci the holding circuit (lAll since the only circuit now existing for the relay 2G includes the high resistance winding of relay 17. Relay 20 upon being .flenergizcd completes the circuit of the slow acting relay 2l, which at its upper and lower iront contacts completes circuits as follows: Y

F rom battery through the upper low resistance winding ot' relay 23 to point 2e from which point one path extends through the lower high resistance winding oi relay 23 and over the lower front contact ci relay 2l to ground. Another path entends from point 24 through the low resistance winding ci relay 25, upper iront contact oi' relay 2l, sleeve contacts oi' plug Pet and jack J4, over the sleeve circuit oi the trunk T and through the resistance e to ground. Relay 25 is energized and locks up relay 21 but relay 24; is differential and does not attract its armav ture.

Should the toll connection be completed hetween the calling and called subscribers by inserting the plug P5 oi a toll cord (l5 in a multiple jack such as J 5 of the toll switching trunlr T with which the calling sub scribers line is associated, a circuit would be completed from battery through resistance 26 in the sleeve of the toll cord7 over the sleeve contacts oi plug P5 and jack J 5, sleeve contacts oi' jack J4 and plug P4, upper iront contact of relay 21, winding ot relay 25, through lower winding of relay 23 and over the lower front contact of relay 21 to ground. The current flow through the lower winding of relay 23 is now sutliciently increased to cause relay 23 to attract its armatu re and cause the glowing of the disconnect lamp 27. The second toll operator theretore withdraws the plug ll.I i'rom the jack J 4,

thereby restoring the holding circuit C4 to normal.

ln case the recording operator had been unable to secure suilicient information i'or completing the connection, she would have passed the ticket containing such information as she had obtained to a directory desk position K, at which position an operator is provided with directories of various cities from which the necessary information concerning the called subscriber may be ob tainec. Since the directory operators position will have calls for information arising from a yery large number oftrunlrs, it is not prarticable to provide a multiple for each trunlr at the directory operators position. Consequently, tie directoryy operator will be connected with the trunk through a B operators position. The directory operator upon receiving the ticket communicates with a E operator over an order wire and requests the operator to insert the plug P2 ot a holding circuit C2 extending to the directory desk position in the jack J2 ci the toll switching trunk T. The directory operizo ator then throws thev holding key K2 to bridge the holding relay 28 across the holding circuit terminating at the B operators position. A circuit is completed from -battery through the low resistance winding of relay 29 to point 30 and thence through the low resistance relay 3l, over the sleeve contacts of plug l and jaclr d2 and over the sleeve contact-s of jack J1 and plug P1, through the winding oi marginal relay 3 to ground. ris only the low resistance windings of relays 29 and 3l are included in series with the relay 3, the latter relay is energized and actuates the disconnect signal V15 of the holding circuit C1 in a manner already described. Relay 8l is energized over the circuit above trate-.d and at its lower iront Contact completes a circuit through the high resistance winding of the differential relay 29, so that said. relay is main` taineddenergized to prevent the actuation ot the disconnect lamp 32.

' The directory operator upon securing such additional information as is necessary to complete the call passes the ticket to a Y toll operator. such as, tor instance, the operator provided with the holding circuit C3. Said toll operator then inserts the plug P3 in the jack d so that the relay 6 is energized over a circuit from battery, middle hack contact of relay 5, winding oi relay 6, sleeve contacts of plug PI... and jack Jg over the sleeve conductor of the toll switching trunk T and through resistance d to ground.

Relay 6 upon being energized completes a circuit 'from ground. over its lower ifi-ont Contact, through the winding ot relay l0, over the upper baclr contact of relay ll, over the sleeve contacts of plug l: and jack J3, over the sleeve contacts ci jack J2 and plug P2, through the winding oi' low resistance relay 3l and through the low resistance winding of relay 29 to battery. The current liow through the upper winding of relay 29 is now sufficiently increased to cause relay 29 to attract its armature and complete the circuit of the disconnect lamp 32. The B operator upon observing the glowing of this lamp withdraws the plug P2 from the jack J2, whereupon the marginal relay l0 is denergized and at its back contact completes a circuit of the relay l1 in a manner already described. Relay l1 upon being energized completes circuits for relays 12 and 14; similar to those already described so that the relay 1.4i is energized and locks up relay 1l? but relay l2 being differential does not attract its armature.

Should another holding circuit suc-h as C4 be associated with the trunk T, or should a toll cord such as C5 be connected to the toll switching trunk, the diiierential relay l2 will be actuated in a manner similar to that already described and will cause the disconnect lamp 22 to glow so that the toll operator will take down the holding cord.

By means of the arrangement above described a holding circuit for a toll switching trunk is provided, said holding circuit being ot' such character that disconnect signals will be transmitted to holding circuits previously associated with the trunk and the holding circuit will in turn receive a disconnect signal upon the subsequent association of any other holding circuit with the trunk.

Furthermore, while the invention has been illustrated in what is believed to be its prei'erred iorm, it will be obvious that the general principles herein disclosed may be embodied in many other organizations widely different from those illustrated without departing from the spirit of the invention as deinined in the following claims.

What is claimed is:

l. The combination with a toll switching trunk, ot a holding` circuit adapted to be associated therewith, means associated with said holding circuit whereby when it is connected with a trunlr disconnect signal will be given for any other holding` circuit which may at that time be associated with the trunk, and signaling means associated with said holding circuit and adapted to be actuated when another circuit is thereafter connected with the trunk.

2. The combination with a toll switching trunk, oi a holding circuit adapted to be associated therewith, means associated with said holding circuit whereby when it is connected with a trunlr a disconnect signal will be transmitted over the sleeve conductor of the trunk to any other holding circuit which may at that time be associated with the ido trunk, and signaling means associated with scid holding circuit and adapted to be actuated when another circuit is thereafter connected with the trunk.

3. rlfhe combination withia toll switching trunk, oit' a holding circuit adapted to be as-` sociated therewith, means associated with said holding circuit whereby when 1t 1s connected with a trunk a disconnect signal will be transmitted over the sleeve conductor of the trunk toany other holding circuit which may at that time be associated with the trunk, and signaling means associated with said holding circuit and adapted to be actuated over the sleeve circuit of the trunk when another circuit is thereafter connected with the trunk.

Ll. The combination with a toll switching trunk, of a holding circuit adapted to be associated therewith, means associated with said holding circuit whereby when it is connected with a trunk a disconnect signal will be given for any other holding circuit which may at that time be associated with the trunk, and signaling means associated with said holding circuit and adaptedto be actuated over the sleeve conductor of the trunk when another circuit is thereafter connected with the trunk.

5. The combination with atoll switching trunk, or a holding circuit adapted to be as' sociated therewith, means whereby when said holding circuit is associated with a trunk a low resistance path is connected to the sleeve conductor of the trunk to operate a marginal signal controlling relay associated with another. holding circuit which may at that time be connected with the trunk, and means to connect a disconnect signal controlling relay with the sleeve conductor of the holding circuit, said relay being arranged to be operated only when another circuit is thereafter associated with the trunk.

6. lThe combination with a toll switching trunk, of a holding circuit adapted to be associated therewith, means whereby when said holding circuit is associated with a trunk a low resistance path is connected to the sleeve conductor of the trunk to operate a marginal signal controlling relay associated with another holding circuit which may at that time be connected with the trunk, and means to connect one winding of a differential signal. controlling` relay with the sleeve conductor of the holding circuit, said relay being arranged so that it is unbalanced and operates due to an increase in current flow over the sleeve conductor of the trunk when another circuit is connected with the trunk.

T. The combination with a toll switching trunk, of a recording operators holding circuit adapted to be associated with the trunk, a toll operators holding circuit adapted to be associated with the trunk at a toll operators position, means associated with said toll operators holding circuit to transmit a disconnect signal to the recording operators holding circuit, and means whereby when a second toll operators holding circuit is connected with the trunk a disconnect signal is transmitted. to said first mentioned. toll op-` erators holding circuit.

ln testimony whereof, I have signed my name to this specification this twenty-first day of December 1918.

OWEN H. LOYNES. 

